There is an ongoing need in the art of membrane-based separations of solutes and solvents for cleaner, more efficient separations that use less membrane surface area. Separation processes utilizing the membrane processes of reverse osmosis, nanofiltration, membrane distillation, pervaporation, supported-liquid membranes, coupled transport, and membrane contactors are all known. It has been suggested to combine reverse osmosis with a phase change process such as solvent exchange, distillation or evaporation for energy-efficient waste-water treatment. Ray et al., 28 J. Memb. Sci. 87 (1986). It has also been suggested to combine reverse osmosis with pervaporation in series to selectively separate water in two stages from a mixture of solvents. See Extended Abstracts, page C23, International Membrane Technology Conference, Sydney, Australia, November 15-17, 1988. However, there has been no recognition in the art of the efficiencies which may be realized in solute/solvent separations by combining certain membrane separations in such a manner that each of the component separation processes is part of a recycle stream wherein the retentate (or raffinate) of one or more solute separation processes comprises the feed of a solvent separation process and the retentate of the solvent separation process forms part of the feed for the solute separation process(es), or vice-versa.